Certain thiolcarbamates and use as herbicides



THIOLCARBAMATES AND USE AS HERBICIDES Harry Tilles, El Cerrito, and JoeAntognini, Mountain View, Calif., assiguors t Staulfer Chemical Company,a corporation of Delaware CERTAIN No Drawing. Application January 17,1956 Serial No. 559,541

13 Claims. (Cl. 71-2.7)

Code Name Ethyl N N-di-n-propylthiolcarbamate. Methyl,N-di-n-propylthiolcarbamate. n-Propyl ,N-di-n-propylthiolcarbamate.Ethyl N,N-pentamethylenethiolcarbamate. n-PropylN,N-pentamethylenethiolcarbamate. IsobutylN.N-di-n-propylthiolcarbamate. n-Butyl N,N-di-n-propylthiolcarbamate.

M N,N-di-n-butylthiolcarbamate. Ethyl N,N-di-n-butylthiolcarbamate.sec-Butyl N,N-di-n-propylthiolcarbamate. n-Amyl N,-di-n-propylthiolcarbamate. n-Propyl N ,N-di-isopropylthiolcarbamate.

Isopropyl N ,N-di-isobutylthiolcarbamate.

Thus, the compounds of the present invention may be represented by theformula:

wherein R is a lower alkyl radical and, R and R are lower alkyl groupswhich have at least three carbon atoms. R and R may be a single alkylgroup having at least five carbon atoms and having two bonds availablenited States Patent for attachment to the nitrogen atom, as in R-1817wherev in N forms a part of a ring structure.

The following illustrative examples demonstrate the methods which may beemployed to make typical compounds of the present invention. In theexamples, all parts are by weight.

Example I (R-1608).Sodium is dispersed in xylene using oleic acid as thestabilizing agent until a particle size of 5-200 microns in diameter isobtained. Dispersion, equivalent to an amount of 16.9 parts (0.733 mole)of sodium, is then transferred to a reactor which has been previouslyflushed out with argon (or other inert gas such as nitrogen). A solutionof 50 parts (0.806 mole) of ethanethiol dissolved in 86 parts of xyleneis then gradually added to the sodium dispersion over an interval of 30minutes. The temperature is maintained at 25 to 36 C. by cooling. Thesodium ethylmercaptide forms as finely divided crystals which make aneasily stirrable slurry. This suspension is heated to reflux, the heatis turned off, and parts (0.733 mole) of di-n-propylcarbarnyl chlorideis added over an interval of 17 minutes to the refluxing slurry. Theheat of reaction is sufficient to keep the xylene refluxing. After allof the di-mpropylcarbamyl chloride has been added, the mixture isrefluxed for an additional 3 hours. It is then cooled, filtered fromsodium chloride which has formed during the reaction, and the solvent isremoved under reduced pressure. The residual liquid is then distilledunder vacuum to give 125.5 parts (90.6% yield) of ethylN,N-di-npropylthiolcarbamate (B.P. (31.5 mm.) 135.5 C.- 137.0 C., n1.4770). The following analysis is obtained:

Calculated for Found CoHguN OS Percent C 57.1 67. 41 Percent H. 10.1 10.26 Percent N- 7. 4 7. 17 16.9 16. 71 189 Example II (R-1607).When thegeneral procedure of Example I is repeated except that 38 parts (0.50mole) of l-propanethiol, sodium dispersion equivalent to 9.2 parts (.40mole) of sodium, and 65.5 parts (0.40 mole) of di-n-propylcarbamylchloride are employed, there is obtained 70.3 parts (86.5% yield) ofn-propyl N,N-din- Example Ill (R1880).When the general procedure ofExample I is repeated except that 9.12 parts (0.12 mole) ofl-p-ropanethiol, sodium dispersion equivalent to 2.3 parts (0.10 mole)of sodium, and 19.2 parts (0.10 mole) of di-n-butylcarbamyl chloride areemployed, there is obtained 20.4 parts (88.3% yield) of n-propyl N,N-di-n-butylthiolcarbamate, (B.P. (15 mm.) 156.5-159" C., n 1.4742

Example IV (R-1854).-When the general procedure of Example I is repeatedexcept that 16.9 parts (0.188 mole) of Z-methyl-l-propanethiol, sodiumdispersion equivalent to 3.45 parts (0.15 mole) of sodium and 24.5 parts(0.15 mole) of di-n-propylcarbamyl chloride are employed, there isobtained 25.2 parts (77.3% yield) of isobutylN,N-di-n-propylthiolcarbamate (B.P. (18 mm.) 143145 0, n 1.4744).

Example V (RJ857).When the general procedure of Example I is repeatedexcept that 16.9 parts (0.188 mole) of l-butanethiol, sodium dispersionequivalent to 3.45 parts (0.15 mole) sodium and 24.5 parts (0.15 mole)of di-n-propylcarbamyl chloride are employed, there is obtained 24.8parts (76% yield) of n-butyl N,N-di-n-propyl- 3 thiolcarbamate (B.P. (19mm.) l51.0-151.5' C., 11 1.4766).

Example VI (R-I866).The general procedure of Example I was followedexcept that 25 parts (0.52 mole) of methanethiol is added in smallportions at 50-60 C. to the sodium dispersion equivalent to 2.3 parts(0.10 mole) of sodium. It is necessary to make sure that unreactedmercaptan does not build up in the reaction mixture since a violentreaction may take place if too much unreacted mercaptan is present withunreacted dispersion. After all of the sodium dispersion has reactedwhich is evidenced by the reaction mixture changing from a purplish hueto a white color, it is heated to reflux and 19.2 parts (0.10 mole) ofdi-n-butylcarbamyl chloride is added. After working up in the usualmanner, there is obtained 13.9 parts (68.5% yield) of methylN,N,-din-butylthiolcarbamate (B.P. (20 mm.) 144-146 C., n 1.4760).

Example VII (R-I870).The general procedure of Example I is followedexcept that 6.2 parts (0.10 mole) of ethanethiol is added to sodiumdispersion equivalent to 2.3 parts (0.10 mole) of sodium at an initialtempera ture of 27 C. and allowing the temperature to rise to 65 C.during the mercaptan addition. The mixture is then heated to reflux and19.2 parts (0.10 mole) of din-butylcarbamyl chloride is added. There isobtained 16.7 parts (76.8% yield of ethyl N,N-di-n-butylthiolcarbamate(B.P. (22 mm.) 154.0-154.5, r25 1.4740).

Example VIII (R-1606).273 parts of anhydrous isopropanol are added to aglass or steel reactor and 3.5 parts (0.153 mole) of sodium is added.The mixture is heated to reflux and the sodium gradually dissolves. Thesolution is then rapidly cooled in ice water. At 50 C., a thick solid ofsodium isopropoxide comes out of solution. The mixture is cooled to 30and then 9.17 parts (0.191 mole) of methanethiol is added rapidly. Thesolid dissolves immediately. The clear solution is heated to boiling and198 parts of isopropanol is distilled off. 89 parts of anhydrous xyleneis then added and 77 parts of isopropanol-xylene mixture is distilled.89 parts more xylene is added and 89 parts of isopropanol-xylene mixtureis distilled. 89 parts more xylene is added and 89 parts of solvent,probably pure xylene by now, is distilled. 49 parts more xylene isadded, the mixture is heated to reflux, and 25 parts ofdi-n-propylcarbamyl chloride is added during 4 minutes. The reaction isnot very exothermic. The mixture is then refluxed for 14 hours, cooled,filtered from salt, the cake is washed with a little xylene and thesolvent is removed under reduced pressure. The residue is then vacuum.distilled and there is obtained 16.7 parts (62.5% yield) of methylN,N-din-propylthiolcarbamate (B.P. (30 mm.) 1285-1295, a 1.4808).

Example IX (R-181 7 ).When the general procedure of Example VIII isrepeated except that 11.7 parts (0.188 mole) of ethanethiol, 3.45 parts(0.15 mole) of sodium and 22.1 parts of N,N,-pentamethylenecarbamylchloride are employed, there is obtained 14.4 parts (55.5% yield) ofethyl N,N-pentamethylenethiolcarbamate (B. P. (31.5 mm.) 1505-1510", 1115168).

Example X (R-1905). When the general procedure of Example VIII isrepeated except that 13.0 parts (0.125 mole) of l-pentanethiol, 2.3parts (0.10 mole) of sodium and 16.4 parts of di-isopropylcarbamylchloride are employed, there is obtained 15.8 parts (68.3%) of n-amylN,N,-di-isopropylthiolcarbamate (B.P. (22 mm.) 145- 149 C., a 1.4721).

Example XI (R-1824).Wl1en the general procedure of Example VIII isrepeated except that 14.3 parts (0.188 mole) of 2-propanethiol, 3.45parts (0.15 mole) of sodium and 22.1 parts (0.15 mole) ofN,N-pentarnethyl- The compounds of the present invention have beenextensively tested as herbicides and have been particularly evaluated aspre-emergence herbicides. Pre-emergence herbicides are ordinarily usedby placing a narrow band of the herbicide over the center of a seededcrop row at time of planting or before crop emerges. If the herbicide isharmless to the desired crop, seeds or seedlings, but phytotoxic to theweed seeds or seedlings most frequently encountered, the crop grows inan almost weedfree environment. Of course, the pre-emergence herbicidemay be used over the entire field, but it is normally used in a narrowband which straddles the crop row and the balance of the weeds arecontrolled by various cultivation methods. The herbicides of the presentinvention are selective toward small seeded annual grasses andbroad-leafed plants, and so are efiective against the most common weedsbut have little effect on such valuable row crops as corn and beans. Thephytocidal composition may be applied to the soil in any convenientform. For instance, it can be dissolved in a solvent, such as acetone,or emulsified and sprayed onto the soil, or it can be combined with adry inert carrier and applied as a dust or as granules; although thecomposition may be applied to an entire crop plot, it is generallypreferred to apply it in a narrow band, say 6", over the seeded row of anewly planted crop. Generally, rates of application of from one-half totwenty pounds per acre of actual area treated will be found suitable.

The following example shows the effect of R-1608 when used to protectcorn from Weeds:

Example XlI.-A field test consisted of applying the compounds at therate of 1, 2, 4, 8 and 10 pounds/80 gallons/acre as pre-emergencetreatments to corn. The compound was dissolved in a small amount ofacetone emulsified in water and applied at the desired rate by mountinga spray nozzle behind the planter packer wheel. A 6" band was appliedand the rates of application are on the basis of the area of actualapplication and not on the total area of the plot treated. The weatherwas sunny, the air temperature 70 F., the soil temperature was 78, andthe seed bed was in good tilth and very dry. Immediately after the test,the plots were sprinkler parison with check plots. The following datawere obenecarbamyl. chloride are employed, there is obtained tained:

TABLE 1 Results 16 days after application Corn Stand 1 Rye 2 Rate I IIIII Av. I II III Av. A, lb.

1 10 8 l0 9. 3 100 100 100 100 2 9 15 8 10. 6 100 100 100 100 Rl608 4 1110 12 11. 0 100 100 100 100 s 12 12 3 9. a 100 100 100 100 10 11 12 s10. 3 100 100 100 100 Check.--- 0 9 6 11 8. 6 0 0 0 0 Oats 2 Dead Nettle2 1 100 100 100 100 100 100 100 100 2 100 100 100 100 100 100 100 100 4100 100 100 100 100 100 100 100 s 100 100 100 100 100 100 100 100 10 100100 100 100 100 100 100 100 Check... 0 0 0 0 0 0 0 (l 0 1 Cornstand-number of plants/10 it. of row. 2 Percent control of weeds.

Example XIII.A number of the compounds were tested at rates ofapplication of and 20 pounds per acre. The method of testing was toplant the seeds in 3" diameter paper cans and drench the material on at30 ml can. The seeds tested were peas, corn, radish, cucumm281om1510010111 Oats Cucumber 4. As .a composition of matter, v n-propylN,N-di-r1- propylthiolcarbamat'e.

Rye

Ge. E

5. As a composition of matter, n-propyl N,N-di-nbutylthiolcarbamate.

6. As a composition of matter, n-amyl, N,N-isopropylthiolcarbamate.

7. The method of combatting weeds comprising apply- Radish TABLE 2 Thedata set TABLE 3 Corn The seeds tested were peas,

sing app Rate/A.,

m N a O 5 a 000 5005000200 50000005000050000005050 79.005400835322002 om mm m mmm mmm mmmm 11 11 55 T m w3118111 00111100000 1 65215560413033W. n n u R 5 55 5 00500005000050.0000 M Ww%w%- m %%m% 7m3 205760581539298 11 111 1 1 5 5 5 5 8 00 O9 00 W w mm mmmw m mmmmlm N11 111 e m D. 000 00000000000 0000 .00 a 00 07 00 n e mmm mmmmwmmmmmwmmmi 111 S G 5 55 55 5 n 5 L 0 0 oooomom 08 00 h G mmm mmm mm1m1m 1 1 u S a Uq 00000000000000000000 .00 00 e 0 -oO 00 S 6 mmmmmmmmwwmmmmmmmmlm l1 11G 55 55 L 0 00 00 G mm mmm mmmmmmlm mm 11 11 n m C 0000000000000000000000 00 I 0 00 90 9 mmmmmwmwmmmmmwmmmmlm l1 1 G 5 555 555 5 5 L00om00000fi4 507 8 &5&95 86 66 G 11 1111 1 s a e P 5 a00000000500500005000 07 00 57 00 G mmm mmmm mm mmmm mm m 11 2 2 2 2 2 2n 2 a 0 oMoWeWoWoMowowowowowowmo mowowowmowo her and either rye or cats.The data set forth in Table 2 were obtained:

a e P 000000 102490 811 G 6 0 00000 M 828282 A W t m d "F" m "n" O p a 17 m 0 0 1 o MEN 0 a a a Example XIV.-A number of compounds were testedin flats in the greenhouse, at 2 /2 and pounds/ 80 gallons of solution/acre. Application made with a fan type corn, squash, snapbeans, rye andoats. forth in Table 3 were obtained:

Compound nozzle at lbs. pressure.

Ge.=Percentage of seeds germinating. Gr.=Growth wherein 10 equals normalgrowth, and 0 indicates no growth.

We claim: 1. As a composition of matter, a compound of the formulaR,s-GN

2. As a composition of matter ethyl N,N-di-n-propylthiolcarbamate.

3. As a composition of matter ethyl N,N-di-n-butylthiolcarbamate.

wherein R is a lower alkyl radical and R and R are identical lower alkylradicals having at least three carbon 70 atoms. atoms.

ing to the soil :1 phytotoxic amount olf ethyl N,N-di-n- ReferencesCited in the file of this patent propylthiolcarbamate. D T ES PAT NT 10.The method of combatting weeds comprising ap- UNITE S AT E S plying tothe soil a phytotoxic amount of ethyl N,N-din- 2*060'733 Hunt et 1936butynhiolcarbamate 2,160,880 Loane et a1. June 6, 1939 11. The method-ofcombatting weeds comprising ap- 2562911 fP July 1951 plying to the soila phytotoxic amount of n-propyl N,N- 2642451 welllard et a1 June 1953 din propylthiolcarbamate Kosmin g' 24! 12. The method of combatting weedscomprising applying to the soil a phytotoxic amount of n-propy1'N,N- 10OTHER REFERENCES di-n-butylthiolcarbamate. Riemschneider et a1.:Monatshefte 84, pp. 5 18-21 13. The method of combatting weedscomprising ap- (1953).

plying to the soil a phytotoxic amount of n-amylN,N-diisopropylthiolcarbamate.

7. THE METHOD OF COMBATTING WEEDS COMPRISING APPLYING TO THE SOIL APHYTOTOXIC AMOUNT OF A COMPOUND HAVING THE FORMULA